1. Field of the Invention
This invention relates to the field of processing materials of all origins, in particular by shredding by means of crushers or of hammer mills, or the like, and has as its object a pre-grinder or pre-shredder.
2. Description of the Related Art
The recovery of metal products from objects that are unserviceable, in particular motor vehicles, by means of crushers or grinders, is generally performed by introducing the objects in a hammer mill, via an introduction ramp equipped with a crushing drum; said hammer mill pulls and shreds the material entering there, by interaction with one or more anvils, which eject and/or evacuate, through screening walls, the mechanical scraps obtained that exhibit a determined size. These scraps are then processed for the purpose of eliminating materials that are unsuitable for reuse and for the purpose of sorting the remaining materials as a function of their metallurgical characteristics.
The processing of very bulky objects or materials necessitates the use of grinders or crushers of large size and high power and therefore with a very high production cost as well as a very high cost of use.
Thus, it has been proposed to use pre-grinders or pre-shredders that make possible a size reduction and fractionation of the very bulky objects and materials, so as to increase the density thereof for the purpose of transporting them, storing them, or burying them, or else processing them in more compact grinders, crushers or granulating machines whose feed openings are of a smaller cross-section.
The pre-grinders or pre-shredders that exist today are, nevertheless, also of large size and high power, generally consisting of one or more slow rotation rotors, which turn in the same or opposite direction.
These rotors shred the material under the interaction of the tools that equip them, and the speed of rotation of the rotors can be identical or different from one rotor to the next. The shafts of these rotors are driven by electric or hydraulic motors, either directly or by means of reducing gears.
In the particular case of pre-shredders or of pre-grinders of automobile bodies, the pre-shredding shafts most often number two, exhibit a large diameter, namely on the order of 500 to 600 millimeters, each weigh nearly 10 tons, and each require a power on the order of 250 Kw to drive them. The length of the line of shafts of such machines is generally between 4 meters and 5 meters, and even more, for a useful working width on the order of 2 meters.
Furthermore, the shredding tools are mounted generally by welding on the large cross-section drive shaft and are therefore not interchangeable. The driving of these shafts, which are mounted at their ends in large cross-section roller bearings, which rest on the lateral walls of the shredder, is performed by motor and reduction gear assemblies, which are fastened laterally on both sides of the housing of these machines or of their feeding chute.
The mounting of these large-sized pieces of equipment, namely reducing gears and motors, outside of these machines has as a result a considerable space requirement of the latter, which is incompatible with a small-capacity processing unit, which must, in essence, be mobile for its possible use on different sites.
Moreover, the motors used are most often hydraulic motors, which are slow, very heavy and mounted freely on the ends of the shafts, or even electric or hydraulic motors connected to said shafts by ordinary reducing gears or planetary gears. Furthermore, in all cases, the drive shafts must be held by bearings equipped with rings or roller bearings, the power or drive elements not being carriers and resting on the ends of these shafts or being fastened to a frame or walls of the machine.
The making of such grinders or pre-shredders is very expensive, and the machines made in this way are very bulky and very heavy.
Furthermore, by WO-A-0185346, a grinding device is known that consists, on the one hand, of a drive assembly and, on the other hand, of a grinding chamber connected in a removable way to the drive assembly, the rotors of the grinding chamber being connected to the drive assembly by means of end-plates or collars. Of course, such a device makes it possible to solve partially the problem of service actions, but necessitates the use of complete sub-assemblies, any action on a grinding chamber entailing the complete disassembly of the latter and its replacement with an identical chamber, no element of the drive sub-assembly making it possible to ensure a direct function for guiding or support of a rotor shaft, for example.
In effect, the shafts of the rotors are mounted on specific roller bearings, their guiding being ensured in a totally autonomous way by their drive assembly. Consequently, using such a device is very expensive necessitating, in fact, the provision of complete, interchangeable grinding chambers, the service actions then being performed in idle time.
By FR-A-2 431 326, a grinder rotor mounting is also known in which the cylinder forming the rotor is integral with the rotor of an electric motor, whose stator is fastened to a through shaft that simultaneously forms the bearing of the cylinder forming the rotor. Such an embodiment obviously makes it possible to reduce the bulk of the rotor assembly of the grinder and drive motor, but necessitates significant and costly disassembly work that is incompatible with the making of low-cost grinders or pre-grinders that are quick and simple to use.